Index: typo3/init.php
===================================================================
--- typo3/init.php	(Revision 6913)
+++ typo3/init.php	(Arbeitskopie)
@@ -88,6 +88,16 @@
 
 
 // *******************************
+// Fix BACK_PATH if the TYPO3_mainDir is set to something else than 
+// typo3/, this is a workaround because the conf.php of the old modules
+// still have "typo3/" hardcoded. Can be removed once we don't have to worry about
+// legacy modules anymore. See RFC / Bug #13262 for more details.
+// *******************************
+if (isset($BACK_PATH) && TYPO3_mainDir != 'typo3/' && substr($BACK_PATH, -7) == '/typo3/') {
+	$BACK_PATH = substr($BACK_PATH, 0, -6) . TYPO3_mainDir;
+}
+
+// *******************************
 // Checking path
 // *******************************
 $temp_path = str_replace('\\','/',dirname(PATH_thisScript).'/');
Index: typo3/sysext/cms/tslib/class.tslib_pagegen.php
===================================================================
--- typo3/sysext/cms/tslib/class.tslib_pagegen.php	(Revision 6913)
+++ typo3/sysext/cms/tslib/class.tslib_pagegen.php	(Arbeitskopie)
@@ -342,7 +342,7 @@
 		/** @var $pageRenderer t3lib_PageRenderer */
 		$pageRenderer = $GLOBALS['TSFE']->getPageRenderer();
 
-		$pageRenderer->backPath = 'typo3/';
+		$pageRenderer->backPath = TYPO3_mainDir;
 
 		if ($GLOBALS['TSFE']->config['config']['moveJsFromHeaderToFooter']) {
 			$pageRenderer->enableMoveJsFromHeaderToFooter();
Index: typo3/sysext/cms/tslib/class.tslib_content.php
===================================================================
--- typo3/sysext/cms/tslib/class.tslib_content.php	(Revision 6913)
+++ typo3/sysext/cms/tslib/class.tslib_content.php	(Arbeitskopie)
@@ -2822,10 +2822,10 @@
 		$typeConf = $conf[$conf['type'] . '.'];
 
 			//add SWFobject js-file
-		$GLOBALS['TSFE']->getPageRenderer()->addJsFile('typo3/contrib/flashmedia/swfobject/swfobject.js');
+		$GLOBALS['TSFE']->getPageRenderer()->addJsFile(TYPO3_mainDir . 'contrib/flashmedia/swfobject/swfobject.js');
 
 		$player = $this->stdWrap($conf[$conf['type'] . '.']['player'], $conf[$conf['type'] . '.']['player.']);
-		$installUrl = $conf['installUrl'] ? $conf['installUrl'] : $prefix . 'typo3/contrib/flashmedia/swfobject/expressInstall.swf';
+		$installUrl = $conf['installUrl'] ? $conf['installUrl'] : $prefix . TYPO3_mainDir . 'contrib/flashmedia/swfobject/expressInstall.swf';
 		$filename = $this->stdWrap($conf['file'], $conf['file.']);
 		if ($filename && $conf['forcePlayer']) {
 			if (strpos($filename, '://') !== FALSE) {
@@ -2931,7 +2931,7 @@
 		$typeConf = $conf[$conf['type'] . '.'];
 
 			//add QTobject js-file
-		$GLOBALS['TSFE']->getPageRenderer()->addJsFile('typo3/contrib/flashmedia/qtobject/qtobject.js');
+		$GLOBALS['TSFE']->getPageRenderer()->addJsFile(TYPO3_mainDir . 'contrib/flashmedia/qtobject/qtobject.js');
 		$replaceElementIdString = uniqid('mmqt');
 		$GLOBALS['TSFE']->register['MMQTID'] = $replaceElementIdString;
 		$qtObject = 'QTObject' . $replaceElementIdString;